Applications2,5-Bis(5-tert-butyl-2-benzoxazolyl)thiophene is used as an optical brightener which converts UV light into visible light. It is also used as a fluorescent brightener for thermoplastic resins of polyvinyl chloride, acrylic resin, polyester fiber, paint, coating and printing ink. It is also useful in detecting the presence of thin-film electrical contact lubricants.